Fadel Hanaa Mohamed, Afifi Rabab, Al-Qabili Dheyazan Mohammed
Department of Animal Hygiene and Zoonoses, Faculty of Veterinary Medicine, Suez Canal University, Ismailia, Egypt.
Department of Wildlife and Zoo Medicine, Faculty of Veterinary Medicine, Suez Canal University, Ismailia, Egypt.
Vet World. 2017 Sep;10(9):1118-1128. doi: 10.14202/vetworld.2017.1118-1128. Epub 2017 Sep 24.
Wild birds are considered silent vectors of some zoonotic water and food borne pathogens of public health significance. Owing to the importance of Shiga toxin producing (STEC) as the most pathogenic among the emerging diarrheagenic groups that can infect man; the present study was designed to detect the occurrence of STEC among wild birds in Egypt.
A total of 177 intestinal content swab samples originating from five wild bird species were investigated for the presence of and STEC by standard culture methods. Suspect STEC isolates were further characterized by serotyping, random amplified polymorphic DNA polymerase chain reaction (RAPD PCR), antimicrobial resistance pattern and PCR detection of , , and genes.
A total of 30 suspect STEC isolates from 30 positive birds' samples were detected and identified on STEC CHROMagar (semi-captive pigeons, 15; house crows, 8; cattle egrets, 3; moorhens, 2; and house teals, 2). 25 isolates were grouped into 13 serogroups (O:20, O:25, O:26, O:27, O:63, O:78, O:111, O:114, O:125, O:128, O:142, O:153, and O:158), while five were rough strains. The distribution of STEC virulence genes among wild birds was as follows: 16 birds carried gene only (nine pigeons [28.1%], six crows [7.1%], and one cattle egret [5.6%]). and genes together were detected in four birds (one cattle egret [5.6%], two moorhens [6.1%], and one house teal, [10%]). Only one pigeon (3.1%) possessed the three alleles. Disk diffusion test results showed that cefixime was the most effective against STEC serotypes with (93.3%) sensitivity, followed by gentamycin (56.7%), and amoxicillin (50%). On the other hand, all the recovered STEC isolates were resistant to cefotaxime, doxycycline, cephalothin, and sulfisoxazole. RAPD fingerprinting using primers OPA-2 and OPA-9 showed that STEC isolates were heterogeneous; they yielded 30 and 27 different clusters, respectively.
Wild birds carry STEC and may add to the contamination of the surrounding environment.
野生鸟类被认为是一些具有公共卫生意义的人畜共患水媒和食源性病原体的无症状传播媒介。由于产志贺毒素大肠杆菌（STEC）在新兴的能感染人类的致泻性菌群中致病性最强，本研究旨在检测埃及野生鸟类中STEC的存在情况。
采用标准培养方法，对来自5种野生鸟类的177份肠道内容物拭子样本进行STEC检测。对疑似STEC分离株进一步进行血清分型、随机扩增多态性DNA聚合酶链反应（RAPD PCR）、抗菌药物耐药模式分析以及stx1、stx2和eae基因的PCR检测。
在STEC CHROMagar培养基上共检测并鉴定出30份来自30只阳性鸟类样本的疑似STEC分离株（半圈养鸽子15份、家鸦8份、牛背鹭3份、黑水鸡2份、绿翅鸭2份）。25株分离株分为13个血清群（O:20、O:25、O:26、O:27、O:63、O:78、O:111、O:114、O:125、O:128、O:142、O:153和O:158），5株为粗糙型菌株。野生鸟类中STEC毒力基因的分布如下：16只鸟仅携带stx1基因（9只鸽子[28.1%]、6只乌鸦[7.1%]和1只牛背鹭[5.6%]）。4只鸟同时检测到stx2和eae基因（1只牛背鹭[5.6%]、2只黑水鸡[6.1%]和1只绿翅鸭[10%]）。仅1只鸽子（3.1%）同时拥有这三个等位基因。纸片扩散试验结果显示，头孢克肟对STEC血清型的敏感性最高（93.3%），其次是庆大霉素（56.7%）和阿莫西林（50%）。另一方面，所有回收的STEC分离株对头孢噻肟钠、强力霉素、头孢噻吩和磺胺异恶唑均耐药。使用引物OPA - 2和OPA - 9进行RAPD指纹图谱分析表明，STEC分离株具有异质性；它们分别产生了30个和27个不同的聚类。
野生鸟类携带STEC，可能会增加周围环境的污染。
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